Method for preparing hydrocarbylhydrocarbyloxysilanes

ABSTRACT

A method for preparing a hydrocarbylhydrocarbyloxysilane of formula RaHpSi(OR)(4-a-b), where each R is independently a hydrocarbyl group and subscript a is 1 to 4 and subscript b is 1 to 2 is disclosed. The method includes heating ingredients including a hydrocarbyl carbonate and a source of silicon and catalyst. The method can be used to make dimethyldimethoxysilane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/728,091 filed on 7 Sep. 2018 under 35 U.S.C. §119 (e). U.S. Provisional Patent Application Ser. No. 62/728,091 ishereby incorporated by reference Technical Field

Hydrocarbylhydrocarbyloxysilanes, such as alkylalkoxysilanes, can beprepared by direct synthesis using a hydrocarbyl carbonate and acatalyzed source of silicon. The method may avoid the need to usehalosilanes and halogenated hydrocarbons in the production ofhydrocarbylhydrocarbyloxysilanes.

BACKGROUND

Hydrocarbylhydrocarbyloxysilanes, such as alkylalkoxysilanes (e.g.,dimethyldimethoxysilane, methyltrimethoxysilane, andtrimethylmethoxysilane) are intermediates in the silicones industryuseful for the production of various silicone fluids and resins.Alkylalkoxysilanes can be produced commercially by alkoxylation ofalkylhalosilanes. When an alkylhalosilane reacts with an alcohol, theresulting alkoxylation reaction produces an alkylalkoxysilane productand a hydrogen halide by-product.

Typically, hydrocarbylhalosilanes are produced commercially by theMueller-Rochow Direct Process, which comprises passing a halogenatedhydrocarbon, such as methyl chloride, over zero-valent silicon in thepresence of a catalyst and various promoters to produce a mixture ofhydrocarbylhalosilanes. A typical commercial process to make zero-valentsilicon comprises the carbothermic reduction of SiO₂ in an electric arcfurnace at extremely high temperatures.

In addition to the Direct Process, alkylhalosilanes have been producedby the alkylation of silicon tetrachloride and variousalkylchlorosilanes by passing the vapors of these chlorosilanes togetherwith an alkyl halide over finely divided aluminum or zinc at elevatedtemperatures. However, this process results in the production of a largeamount of by-product aluminum chloride or zinc chloride, which is costlyto dispose of on a commercial scale.

There is an industry need to produce hydrocarbylhydrocarbyloxysilanes inprocesses that minimize the use of halogenated hydrocarbons and/orminimize production of undesirable by-products.

SUMMARY

A method for preparing a hydrocarbylhydrocarbyloxysilane comprises:heating at a temperature of 150° C. to 400° C., ingredients comprising

a) a hydrocarbyl carbonate, and

b) a catalyzed source of silicon, and

optionally c) hydrogen, and

thereby forming a reaction product comprising thehydrocarbylhydrocarbyloxysilane, where thehydrocarbylhydrocarbyloxysilane has formula R_(a)H_(b)Si(OR)_((4-a-b)),where each R is independently a hydrocarbyl group and subscript a is 1to 4 and subscript b is 0 to 2.

DETAILED DESCRIPTION

The hydrocarbyl carbonate used as ingredient a) in the method describedherein is commercially available. The hydrocarbyl carbonate may haveformula:

where each R¹ and each R² are independently a hydrocarbyl group. R¹ andR² may each be independently selected from the group consisting ofalkyl, alkenyl, alkynyl, and aryl. Alternatively, R¹ and R² may eachindependently be an alkyl group, an alkenyl group or an aryl group.Alternatively, R¹ and R² may each be an alkyl group. Alternatively, oneof R¹ and R² may be an alkyl group and the other of R¹ and R² may be anaryl group. The alkyl groups for R¹ and R² may each have 1 to 10 carbonatoms, alternatively 1 to 6 carbon atoms, and alternatively 1 to 4carbon atoms. The alkenyl and/or alkynyl groups for R¹ and R² may eachhave 2 to 10 carbon atoms, alternatively 2 to 6 carbon atoms, andalternatively 2 to 4 carbon atoms. The aryl groups for R¹ and R² mayeach have 6 to 10 carbon atoms, alternatively 6 to 8 carbon atoms.Alkyl, alkenyl, and alkynyl groups containing at least three carbonatoms may have a branched or unbranched structure. Alternatively, R¹ andR² may each be Me, Et, Pr, hexyl, or Ph. Alternatively, R¹ and R² mayeach be Me or Et. Alternatively, R¹ and R² may each be Me. Examples ofhydrocarbyl carbonates useful in the method described herein includedimethyl carbonate, diethyl carbonate, methyl phenyl carbonate, diphenylcarbonate, dibenzyl carbonate, and diallyl carbonate, and they arecommercially available from Sigma-Aldrich. The amount of hydrocarbylcarbonate may be 70 mol % per hour based on the amount of silicon iningredient b), alternatively 50 mol % to 100 mol % per hour based on theamount silicon in ingredient b).

Ingredient b) is a catalyzed source of silicon. The silicon iningredient b) is reactive with ingredient a). Ingredient b) may be acopper silicide or a contact mass such as that used in theMueller-Rochow Direct Process, described above, which comprises siliconmetal and a catalyst such as copper.

In one embodiment, ingredient b) is a copper silicide. The coppersilicide used as ingredient b) in the method described above may have anempirical formula Cu_(z)Si_(y)Al_(x)Sn_(w)Ti_(v) where subscripts z, y,x, w, and v represent the molar amounts of each element present, andz>0, y>0, x≥0, w≥0, and v≥0, with the proviso that z>y. Alternatively,2.5≤z≤8, and y=1. When x=w=v=0, then the copper silicide is a binarycopper silicide. Alternatively, 3<z≤7 and y=1.

The copper silicide useful in the method may be a binary coppersilicide, which is commercially available. “Binary copper silicide”means a material including both silicon and copper that are intermixedat an atomic level, and the arrangement of the atoms can be describedusing well known crystallographic principles and models. Example phasesof binary copper silicides are found in the phase diagram (Okamoto H.,J. Phase. Equilib., Vol. 23, 2002, p 281-282) and include, but are notlimited to: Cu_(0.88)Si_(0.12), Cu_(0.85)Si_(0.15), Cu_(0.83)Si_(0.17),Cu_(4.15)Si_(0.85), Cu₁₅Si₄, and Cu_(3.17)Si. In addition, binary coppersilicide may further include Cu and Si individually, provided that theamount of Cu present is not sufficient to cause sintering in the methoddescribed herein. Exemplary binary copper silicides include, but are notlimited to, Cu₇Si, Cu₅Si, Cu₄Si, and Cu₃Si. Other exemplary binarycopper silicides include, but are not limited to, κ-Cu₇Si, γ-Cu₅Si,δ-Cu_(4.88)Si, ε-Cu₄Si, and η-Cu₃Si. Other exemplary binary coppersilicides include, but are not limited to η-Cu₃Si, η′-Cu₃Si, η″-Cu₃Si,η-Cu_(3.17)Si, η′-Cu_(3.17)Si, and η″-Cu_(3.17)Si. Alternatively, thebinary copper silicide may be Cu₅Si.

In one embodiment, the ingredients consist of ingredient a) and binarycopper silicide, i.e., without hydrogen, used as ingredient b). In thisembodiment, the binary copper silicide is typically at least 99.0% pure,alternatively 99.5% pure, or greater. The binary copper silicide may be99.0% pure to 99.99% pure, alternatively 99.5% pure to 99.9% pure.

Alternatively, when ingredient b) is a copper silicide, the coppersilicide may further comprise an additional metal, i.e., a differentmetal included in addition to copper and silicon. In this instance,additional metal may act as a co-catalyst even though it is incorporatedinto the copper silicide, and the copper silicide may be ternary orhigher. The additional metal may be selected from aluminium (Al), tin(Sn), titanium (Ti), or a combination of two or more of Al, Sn, and Ti.This copper silicide may have an empirical formulaCu_(b)Si_(c)Al_(d)Sn_(e)Ti_(f) where subscripts b, c, d, e, and f,represent the molar amounts of each element present, and b>0, c>0, d≥0,e≥0, and f≥0; with the provisos that at least one of d, e, and f is not0. In this copper silicide, b>c. Alternatively, 2.5≤b≤8, c=1, and one ofd, e, and f is greater than 0. Alternatively, the additional metal maybe selected from the group consisting of Al and Sn. Alternatively, theadditional metal may be Al. Alternatively, the additional metal may beSn. Alternatively, the copper silicide may have formula(M)_(i)(Cu_(k)Si)_(j), where M is the additional metal selected from Al,Sn, and Ti. Alternatively, M may be Sn or Ti. Alternatively, M is Sn.Subscript i represents the molar amount of the additional metal, and0<i≤1. Subscript k represents the molar amount of copper relative tosilicon, and 2.5≤k=8. Alternatively, 3≤k≤5. Subscript j represents themolar amount of copper and silicon collectively, relative to the amountof the additional metal, and j has a value sufficient that a quantity(i+j)=100. Exemplary copper silicides in this embodiment include ternaryintermetallic compounds of Cu, Si, and Al; of Cu, Si, and Sn; and of Cu,Si, and Ti. Alternatively, the copper silicide in this embodiment mayhave formula (M_(m):Cu_((1-m)))_(n)Si, where M is as described above,subscript 0<m≤0.01; alternatively 0.001≤m≤0.01 and 2.5≤n≤8.Alternatively, M is selected from the group consisting of Al, Sn, andTi. Alternatively, M is selected from the group consisting of Ti and Sn.Alternatively, M is Sn. Alternatively, M is Ti. Exemplary coppersilicides of this formula include (Sn_(0.01)Cu_(0.99))₅Si,(Ti_(0.01)Cu_(0.99))₅Si, (Sn_(0.01)Cu_(0.99))₄Si, and(Ti_(0.01)Cu_(0.99))₄Si, (Al_(0.01)Cu_(0.99))₃Si. These copper silicidesare commercially available. Alternatively, they may be prepared byconventional methods, such as from the melt of the individual elementsat predetermined stoichiometry using a heating apparatus such aselectric arc melter. Alternatively, the ternary intermetallic compoundsmay be prepared by a process comprising vacuum impregnating two metalhalides on silicon particles thereby producing a mixture, andmechanochemically processing the mixture under an inert atmosphere,thereby producing a reaction product comprising the ternary coppersilicides. The copper silicides described above may be prepared in thismanner.

Alternatively, the method may further comprise adding ingredient d) apromoter or co-catalyst. Ingredient d) may be used, for example, in theembodiment in which a binary copper silicide is used as ingredient b).In this embodiment, ingredient d) is a separate metal or compound addedwith the copper silicide, i.e., not a metal incorporated in the ternaryor higher copper silicide. Ingredient d) may be selected from Al, Sn,Ti, or a combination of two or more of Al, Sn, and Ti. The catalyst maybe metallic, e.g., metallic Sn or metallic Al. Alternatively, thecatalyst may comprise one or more compounds of Al, Sn, or Ti. Compoundsare exemplified by halides, e.g., chlorides such as aluminium chloride(AlCl₃), stannous chloride (SnCl₂), and stannic chloride (SnCl₄), and/orzinc chloride (ZnCl₂); oxides such stannous oxide (SnO₂), andphosphides. The amount of ingredient d) can vary depending on the typeand amount of species selected from the catalyst and desireddistribution of the hydrocarbylhydrocarbyloxysilane species produced.However, the amount of catalyst may range from 1000 ppm to 3%,alternatively 0.5% to 3%, alternatively 1% to 3%, and alternatively 1%to 2%, based on the weight of ingredient b).

In an alternative embodiment, ingredient b) is a contact mass such asthat used in the Mueller-Rochow Direct Process. The contact masscomprises silicon metal, a catalyst, and optionally a promoter. Thecatalyst may be copper, silver or nickel, alternatively copper. Any formof copper, silver, or nickel may be used. For example, when the catalystis copper, the catalyst may be selected from elemental copper, copperalloys, copper compounds, and mixtures thereof. Examples of the coppercompounds include, but are not limited to, granular copper powder,stamped copper, cuprous oxide, cupric oxide, cupric chloride, cuprouschloride, copper nitride, copper hydroxide, copper formate, and mixturesof two or more of the preceding copper compounds. Methods of making suchcopper compounds are known in the art, and the compounds are availablecommercially. The contact mass may include an amount of copper or coppercompound sufficient to provide 2 ppm to 10%, alternatively 0.2% to 10%of elemental copper based on the weight of elemental silicon in thecontact mass.

The promoter can be any element or its compounds that accelerate orcatalyze the Direct Process. Promoters include, but are not limited to,phosphorous, phosphorous compounds, zinc, zinc compounds, tin, tincompounds, antimony, antimony compounds, arsenic, arsenic compounds,cesium, cesium compounds, aluminium and aluminium compounds, calcium,calcium compounds, titanium, titanium compounds, and mixtures of atleast two of the preceding promoters. Alternatively, the promoter maycomprise one or more elements selected from zinc, tin, iron, phosphorousand aluminium. One or more promoters may be present in the contact massin amounts such that elemental phosphorus may be present in amounts ofup to 2500 ppm, alternatively 250 to 2500 ppm based on the weight of thesilicon in the contact mass. Elemental tin may be present in an amountof up to 200 ppm, alternatively 5 ppm to 200 ppm, based on the weight ofsilicon in the contact mass. Elemental aluminium and elemental iron mayeach be present in amounts up to 1%, alternatively 0.02% to 1%, based onthe weight of silicon in the contact mass. Elemental zinc may be presentin an amount up to 10,000 ppm, alternatively 100 to 10,000 ppm based onthe weight of silicon in the contact mass. Exemplary phosphoruspromoters include elemental phosphorus, metal phosphides such as zincphosphide. Certain compounds may include more than one promoter, such astin phosphide. Alternatively, catalyst and promoter may be provided inone compound, such as when a copper-zinc alloy such as brass, acopper-antimony alloy, or a copper-phosphorous alloy, such as cuprousphosphide, is combined with silicon metal to form the contact mass.

When promoter is present, the combination of catalyst and promoter maybe present in the contact mass in a combined amount of 3 ppm to 10%based on the weight of silicon metal in the contact mass, alternatively3 ppm to 5%. One skilled in the art would recognize that metallurgicalgrade silicon used in preparation of the contact mass may contain one ormore impurities that act as a catalyst and/or a promoter as describedabove. Examples of contact masses and how to make them are described inpatents, for example, U.S. Pat. Nos. 8,962,877; 5,596,119; 5,059,343;4,966,986; 4,965,388; 4,962,220; 4,946,978; 4,898,960; 4,762,940;4,602,101; and U.S. Re. 33,452. In one embodiment, ingredient b) is acontact mass comprising silicon, copper, and tin.

The method can be performed in any reactor suitable for the combining ofgases and solids or any reactor suitable for the combining of liquidsand solids. For example, the reactor configuration can be a batchvessel, packed bed, stirred bed, vibrating bed, moving bed,re-circulating beds, or a fluidized bed. Alternatively, the reactor formay be a packed bed, a stirred bed, or a fluidized bed. To facilitatereaction, the reactor may have means to control the temperature of thereaction zone, i.e., the portion of the reactor in which the ingredientsare in contact.

The temperature of the reactor in which the ingredients are contacted isat least 150° C., alternatively 150° C. to 400° C.; alternatively 200°C. to 350° C.; alternatively 200° C. to 300° C.; alternatively 250° C.to 350° C.; alternatively 350° C. to 400° C.; alternatively 370° C. to400° C.; and alternatively 300° C. to 400° C. Without wishing to bebound by theory, it is thought that if temperature is less than 150° C.,then the reaction may not proceed at a sufficient speed to produce thedesired product; and if the temperature is greater than 400° C., theningredient a) and/or hydrocarbylhydrocarbyloxysilanes in the reactionproduct may decompose.

The pressure at which the ingredients are contacted can besub-atmospheric, atmospheric, or super-atmospheric. For example, thepressure may range from greater than 0 kilopascals absolute (kPa) to2000 kPa; alternatively 100 kPa to 1000 kPa; and alternatively 101 kPato 800 kPa.

The mole ratio of ingredient a) to ingredient b) may range from 10,000:1to 0.01:1, alternatively 100:1 to 1:1, alternatively 20:1 to 5:1,alternatively 20:1 to 4:1, alternatively 20:1 to 2:1, alternatively 20:1to 1:1, and alternatively 4:1 to 1:1. The amounts of ingredient a) andingredient b) are sufficient to provide the mole ratio described above.

The residence time for ingredient a) is sufficient for the ingredient a)to contact ingredient b) and form the reaction product. For example, asufficient residence time may be at least 0.01 s, alternatively at least0.1 s, alternatively 0.1 s to 10 min, alternatively 0.1 s to 1 min, andalternatively 0.5 s to 10 s. The desired residence time may be achievedby adjusting the flow rate of ingredient a), or by adjusting the totalreactor volume, or by any combination thereof.

Ingredient b) is used in a sufficient amount. A sufficient amount ofingredient b) is enough to form the reaction product, when ingredient a)is contacted with ingredient b). The exact amount of ingredient b)depends upon various factors including the type of reactor used (e.g.,batch or continuous), the residence time, temperature, the molar ratioof ingredient a) to ingredient b), and the particular species selectedfor ingredient a) used. However, a sufficient amount of ingredient b)may be at least 0.01 milligram per cubic centimeter (mg/cm³) of reactorvolume; alternatively at least 0.5 mg/cm³ of reactor volume, andalternatively 1 mg/cm³ of reactor volume to the maximum bulk density ofthe ingredient b), alternatively 1 mg/cm³ to 5,000 mg/cm³ of reactorvolume, alternatively 1 mg/cm³ to 1,000 mg/cm³ of reactor volume, andalternatively 1 mg/cm³ to 900 mg/cm³ of reactor volume.

There is no upper limit on the time for which the method is conducted.Without wishing to be bound by theory, it is thought that the method maybe performed indefinitely to make the reaction product as ingredient a)is contacted with ingredient b). For example, the method may beconducted for at least 0.1 s, alternatively 1 s to 30 hours (h),alternatively 1 s to 5 h, alternatively 1 min to 30 h, alternatively 3 hto 30 h, alternatively 3 h to 8 h, and alternatively 3 h to 5 h.

The method described herein may also comprise purging before contactingthe ingredients. Purging may be conducted to remove unwanted gaseous orliquid materials. Unwanted materials are, for example, air, O₂ and/orH₂O. Purging may be accomplished with a gas such as argon (Ar), helium(He), hydrogen (H₂), and/or nitrogen (N₂); alternatively H₂;alternatively an inert gas such as Ar, He, and/or N₂. Purging may beperformed by feeding the gas into the reactor at ambient or elevatedtemperature, such as 25° C. to 300° C.

The method may further comprise vaporizing ingredient a), such as byknown methods, e.g., heating or passing a carrier gas through areservoir containing ingredient a), before contacting with ingredientb).

The method may further comprise recovering the reaction product, forexample, to purify one or more of the hydrocarbylhydrocarbyloxysilanesin the reaction product produced by the method. The reaction product maybe recovered by, for example, removing gaseous reaction product and anyother vapors from the reaction product followed by condensation of thevapors and/or isolation of one or more compounds from any othercompounds in the reaction product by a technique such as solventextraction and/or distillation.

The hydrocarbylhydrocarbyloxysilanes produced by the present method mayhave formula R_(a)H_(b)Si(OR)_((4-a-b)), where each R is independently ahydrocarbyl group and subscript a is 1 to 4 and subscript b is 0 to 2.Each R be independently selected from the group consisting of alkyl,alkenyl, alkynyl, and aryl. Alternatively, each R may independentlyselected from an alkyl group, an alkenyl group or an aryl group.Alternatively, each R may be an alkyl group. The alkyl groups for R mayeach have 1 to 10 carbon atoms, alternatively 1 to 6 carbon atoms, andalternatively 1 to 4 carbon atoms. Alkyl groups are exemplified by Me,Et, Pr, and Bu. The alkenyl and/or alkynyl groups for R may each have 2to 10 carbon atoms, alternatively 2 to 6 carbon atoms, and alternatively2 to 4 carbon atoms. The aryl groups for R may each have 6 to 10 carbonatoms, alternatively 6 to 8 carbon atoms. Alkyl, alkenyl, and alkynylgroups containing at least three carbon atoms may have a branched orunbranched structure. Alternatively, each R may be independentlyselected from Me, Et, Pr, hexyl, or Ph. Alternatively, each R may be Meor Et. Alternatively, each R may be Me. Alternatively, subscript a maybe 1 to 2 and subscript b may be 0 to 1. Alternatively, thehydrocarbylhydrocarbyloxysilanes produced by the method may have formulaR_((4-a))Si(OR)_(a), where R and a are as described above.

Examples of hydrocarbylhydrocarbyloxysilanes produced by the presentmethod include dimethylmethoxysilane (Me₂HSiOMe), trimethylmethoxysilane(Me₃SiOMe), methyldimethoxysilane (MeHSi(OMe)₂), dimethyldimethoxysilane(Me₂Si(OMe)₂), methyltrimethoxysilane (MeSi(OMe)₃), tetramethoxysilane(TMOS), and combinations of two or more of Me₂HSiOMe, Me₃SiOMe,MeHSi(OMe)₂, Me₂Si(OMe)₂, Me₂Si(OMe)₃, and TMOS. Alternatively, theproduct may comprise methyltrimethoxysilane, dimethyldimethoxysilane,trimethylmethoxysilane, and tetramethoxysilane.

The hydrocarbylhydrocarbyloxysilanes (such as alkylalkoxysilanes) may beused as reactants to make polyorganosiloxane resins with crosslinkedsiloxane networks. Such polyorganosiloxane resins are useful, forexample, for making high temperature coatings, as thermal and electricalinsulating coatings, as hydrophobic coatings, and/or as matrices forfiber reinforced composites. Dialkyldialkoxysilanes, such asdimethyldimethoxysilane, are useful as reactants for producingpolydialkylsiloxane polymers, such as polydimethylsiloxanes.

Examples

These examples are intended to illustrate some embodiments of theinvention and should not be interpreted as limiting the scope of theinvention set forth in the claims. Copper silicide of formula Cu₅Si with99.5% purity and methyl phenyl carbonate were purchased from Alfa Aesar.Cu₅Si with 97% purity was purchased from Gelest. Dimethyl carbonate waspurchased from ACROS.

Reference Example 1—Copper Silicide Preparation

Copper silicide ingots were prepared by high temperature melting of theprecursor materials using a MRF model SA200 laboratory arc-melter. Thegeneral formula was M₅Si with M being either pure Cu or a mixture ofcopper with an additional metal other than copper in a ratio of copperto the other metal of 99:1, atomic ratio. The appropriate weightquantities of the precursor materials were mixed together and placedinto an oxygen-free copper crucible. The process of forming the silicidewas performed under Argon (Ar) atmosphere (80-90 kPa) using a standardceriated tungsten electrode in three one minute sessions. Between thesessions the sample ingot was cooled to below 200° C., removed, surfacecleaned and placed upside down back into the crucible. The subsequentrepeated re-melting of the crucible contents assured a good homogeneityof the final copper silicide ingot, which was first confirmed by avisual inspection of the ingot and then by the XRD characterization. Theinteraction between the melt and the crucible was minimal, as no wettingof the crucible surface by the melt was observed during the synthesis.

The copper silicide ingots were crushed with a vise to small chunks. Thecrushed ingots were then ground in air for 10 minutes using a SpexSamplePrep™ model 8000D mill. A 316 stainless steel ball mill vial andfour 7 mm diameter tungsten carbide balls were used in the grindingprocess, which resulted in formation of a copper silicide powder withthe average particle size of <150 μm, as determined by sieving (80 meshsieve). A tungsten carbide ball mill vial and two 10 mm tungsten carbidebearings were also used in the grinding process.

The reactor apparatus included a gas flow preparation system, an 18″long (0.25″ outer diameter and 0.15″ diameter) quartz reactor tube, atube furnace, an in-line gas sampling valve, and a GC equipped withmass-selective and thermal conductivity detectors. The gas flowpreparation system allowed for an individual supply or pre-mixing of anyof two gases or gas streams: H₂ and Ar. The gas flows were controlled inthe 2-100 sccm range for Ar and H₂ using Brooks 5850 thermal mass flowcontrollers. The mass flow controllers were equipped with metal sealvalves and pre-calibrated for the specific gases by the manufacturer.The hydrocarbyl carbonate was injected into the reactor tube via a ⅛″tube which was fed by a pump. The pressure of the gas flow entering thereactor was monitored by a 1-2000 psi pressure range capacitancepressure transducer (0.1 psi accuracy) powered via an electronic readoutunit. All gas lines between the mass flow controllers and reactor inletwere made of stainless steel tubing; all gas valves were of a ball-typelubricant-free from Swagelok®; all gas connectors, joints and other flowcomponents were of a Swagelok® tube type. The Parker® fluoro-polymercompression fittings were used to connect the quartz reactor tube to thegas preparation system and the sampling valve. The front portion of thereactor before the furnace and the area between the ends of the furnacewere heated at 110° C. by heating tape controlled by two AC currentvariable transformers. A Lindberg/Blue M HTF55122A type furnace with the0-1200° C. temperature range was used for the reactor temperaturecontrol. The furnace PID controller allowed for better than 0.5° C.temperature stability at 350° C., which was the reaction temperatureused in these examples. The reactor tube outlet was connected to thein-line heated six-way sampling valve (Valco Vici®). The 1/16″ O.D.stainless steel tube gas sampling loop attached to the valve was of 100μl volume. The temperature of the valve and the loop was maintained at200° C. The gas lines between the reactor unit and sampling valve andbetween the sample valve and the bubbler were heated by an electricheating tape. The temperature of the heated tape maintained at 130° C.by an AC current variable transformer.

The quantitative analysis of the reactor effluent was performedchromatographically by using the thermal conductivity detector (TCD) ofthe on-line gas GC instrument. The identity of the compounds in thereactor effluent was determined using the mass-selective (MS) detector.The GC/MS instrument was an Agilent 5795 GC attached to a 5975C MS. Thepreferred GC conditions were to use 30 meter SPB-octyl LTM columnsinitially at 50° C. and then ramping to 150° C. (100° C./min) whileholding for several minutes and cooling back to 25° C. Pressure was setat 15 psi and a flow rate of around 40 ml/min. A 25:1 split flow ratiowas used, and data were collected for 10-13 minutes per sampling run(depending on substrate). A 200° C. inlet temperature was used to allowhigher boilers to reach the column. Injections were performedautomatically using the 6-way valve.

Example 1—Copper Silicide and Dimethyl Carbonate

In each trial, 3.09 g of a copper silicide that contained 0.25 g ofsilicon was placed in the ¼″ quartz tube and this was placed in thereactor. The copper silicide was treated at 300° C. under a flow of 20sccm hydrogen for 30 minutes to remove any surface oxides that may havebeen present. Then, the reactor was heated at 350° C. under a flow of 5sccm Ar. Next, the desired flow rate of 10 microliters/min (whichcorresponds to 2.6 sccm of gaseous dimethyl carbonate) was started. Thereaction progress was monitored by sampling and analyzing the reactorgas effluent as described above. Table 1 (see last page of thisapplication) shows the copper silicide sample used and the amounts (mol%) of each species present in the reaction product. These examplesshowed that use of a binary copper silicide and use of a ternary coppersilicide having certain additional metals present in addition to copperand silicon can be used to produce a reaction product with highselectivity to dimethyldimethoxysilane.

Example 2—Contact Mass

In an additional trial, a sample of silicon (HSC 890 from HemlockSemiconductor Corporation of Hemlock, Mich., U.S.A.) was combined withcopper catalyst (CuCl) and tin promoter (SnCl₂) to form a contact mass.Three samples were also prepared containing HSC890 and 1000 ppmtitanium, 1000 ppm aluminum, and 1000 ppm titanium and aluminum each.These three samples were then combined with copper catalyst and tinpromoter as described above, and the resulting contact masses wereevaluated using the equipment and procedure described above. The resultscan be seen in Table 2.

Example 3—Copper Silicide and Diethyl Carbonate

An amount of 3.09 g of Alfa Aesar Cu₅Si was placed in a ¼″ quartz tubeand this was placed in the reactor. The Cu₅Si was heated to 300° C.under a flow of 20 sccm hydrogen for 30 minutes to remove any surfaceoxides that may have been present. Then, the carrier gas was switched to5 sccm Ar. Next, 0.2 ml of diethyl carbonate was injected into thereactor. After priming, the flow rate was set to 0.0051 ml/min ofdiethyl carbonate (1 sccm diethyl carbonate). The reaction progress wasmonitored by sampling the gas effluent periodically. The TCD integralvalues of the reaction intermediates were input into a spreadsheet todetermine values such as selectivity, rate, conversion, and siliconremoved. After 60 minutes the tube effluent contained 58 mol %EtSi(OEt)₃, 41 mol % Si(OEt)₄, and >1% disiloxanes and other ethylsilanes. The conversion of diethyl carbonate to ethylethoxysilanes was34.8 mol %. The integral silanes production rate was 19.3 μmol/min.

Example 4—Copper Silicide and Diphenyl Carbonate

In an argon filled glove box 0.865 g (2.5 mmol) Cu₅Si (high purity) wasplaced in a 38 mL Ace Glass pressure tube (1″×10″ with a #15 thread andinner viton o-ring) and 1.06 g (5 mmol) of diphenyl carbonate was alsocharged. The tube was removed from the glove box and placed in a heatingblock and heated to 300° C. The portion of the tube protruding from theheating block was wrapped in aluminum foil. After running for 20 hours,the reactor was cooled and then the contents were taken up in CDCl₃. Theresulting solution was analyzed by GCMS, which showed Si(OPh)₄,PhSi(OPh)₃, and Ph₂Si(OPh)₂ with the ratio of starting material toSi(OPh)₄ being 1:0.045, the ratio of Ph₂Si(OPh)₂:Si(OPh)₄ being 0.041:1,and the ratio of PhSi(OPh)₃:Si(OPh)₄ being 0.22:1.

Example 5—Binary Copper Silicide with SnCl₂ Promoter

The procedure of example 1 was repeated, except 3.09 g of a physicalmixture of 8 mg of SnCl₂ (8 mg) and the balance Cu₅Si was placed in thereactor instead of the copper silicide of example 1. The results are inTable 1. Example 5 shows that a separate metal compound added with thecopper silicide, i.e., not a metal incorporated in the ternary or highercopper silicide can also provide the benefit of the method describedherein.

INDUSTRIAL APPLICABILITY

The method described herein is capable of preparinghydrocarbylhydrocarbyloxysilanes without need of preparation of ahydrocarbylhalosilane first and then converting thehydrocarbylhalosilane via, e.g., an alkoxylation reaction. The methodconditions are similar to those of Rochow-Muller direct process, exceptwith different starting materials. Without wishing to be bound bytheory, it is thought that the method described herein is a moreenvironmentally friendly approach (as compared to the Rochow-Mullerdirect process) that reduces or avoids the need to use halogenatedhydrocarbons (such as methyl chloride) which are considered lessenvironmentally friendly agents (due to the subsequent HCl generationupon preparation of siloxane polymers). Therefore, the present methodmay be performed without adding any halide of formula R′X (where R′ ishydrogen or a hydrocarbyl group and X is a halogen atom as describedabove) during step 1), as recited in claim 1. Furthermore, the presentmethod may be performed without adding halosilanes during step 1), whichcan also result in HCl generation upon preparation of siloxane polymers.

Without wishing to be bound by theory, it is thought that addingingredient c) hydrogen while feeding the dimethyl carbonate may resultin a decrease in reaction rate (as compared to the same conditions wherehydrogen is not used), and may increase the relative amounts of Me₃SiOMeand MeSi(OMe)₃ species in the reaction product. Without wishing to bebound by theory, it is thought that when diethyl carbonate used in placeof dimethyl carbonate under the conditions of the examples above, willprovide selectivity towards ethyl triethoxysilane in the reactionproduct; and methyl phenyl carbonate used in place of the dimethylcarbonate will improve selectivity toward the formation of Si-Me andSi—OPh bonds (instead of Si-Ph and Si—OMe bonds).

The Brief Summary of the Invention and the Abstract are herebyincorporated by reference. All ratios, percentages, and other amountsare by weight, unless otherwise indicated. The articles ‘a’, ‘an’, and‘the’ each refer to one or more, unless otherwise indicated by thecontext of the specification. Abbreviations used herein are defined inTable A, below.

TABLE A Abbreviations Abbrev. Word % Percent AC alternating current Bu“Bu” means butyl and includes branched and linear structures such asiso-butyl and, n-butyl. ° C. degrees Celsius Et Ethyl GC gaschromatograph and/or gas chromatography ICP-AES inductively coupledplasma atomic emission spectroscopy ICP-MS inductively coupled plasmamass spectrometry kPa Kilopascals Me Methyl mg Milligram mL Millilitersmol mole Ph Phenyl Pr “Pr” means propyl and includes branched and linearstructures such as iso-propyl and, n-propyl. s Seconds sccm standardcubic centimeters per minute TCD thermal conductivity detector μmolmicromole Vi Vinyl

“Metallic” means that the metal has an oxidation number of zero.

“Purging” means to introduce a gas stream into a container to removeunwanted materials.

“Treating” means to introduce a gas stream into a container to pre-treata component before contacting the component with another component.Treating includes contacting ingredient b) with the gas stream to reduceor otherwise activate ingredient b) before contacting it with ingredienta).

“Residence time” means the time which a component takes to pass througha reactor system in a continuous process, or the time a component spendsin the reactor in a batch process. For example, residence time instep 1) refers to the time during which one reactor volume of ingredientb) makes contact ingredient a) as ingredient b) passes through thereactor system in a continuous process or during which ingredient b) isplaced within the reactor in a batch process. Alternatively, residencetime may refer to the time for one reactor volume of reactive gas topass through a reactor charged with ingredient b). (E.g., residence timeincludes the time for one reactor volume of ingredient a) to passthrough a reactor charged with ingredient b).

The disclosure of ranges includes the range itself and also anythingsubsumed therein, as well as endpoints. For example, disclosure of arange of 2.0 to 4.0 includes not only the range of 2.0 to 4.0, but also2.1, 2.3, 3.4, 3.5, and 4.0 individually, as well as any other numbersubsumed in the range. Furthermore, disclosure of a range of, forexample, 2.0 to 4.0 includes the subsets of, for example, 2.1 to 3.5,2.3 to 3.4, 2.6 to 3.7, and 3.8 to 4.0, as well as any other subsetsubsumed in the range.

With respect to any Markush groups relied upon herein for describingparticular features or aspects of various embodiments, it is to beappreciated that different, special, and/or unexpected results may beobtained from each member of the respective Markush group independentfrom all other Markush members. Each member of a Markush group may berelied upon individually and or in combination with any other member ormembers of the group, and each member provides adequate support forspecific embodiments within the scope of the appended claims. Forexample, disclosure of the Markush group: alkyl, alkenyl and arylincludes the member alkyl individually; the subgroup alkyl and aryl; andany other individual member and subgroup subsumed therein.

It is also to be understood that any ranges and subranges relied upon indescribing various embodiments of the present disclosure independentlyand collectively fall within the scope of the appended claims, and areunderstood to describe and contemplate all ranges including whole and/orfractional values therein, even if such values are not expressly writtenherein. The enumerated ranges and subranges sufficiently describe andenable various embodiments of the present disclosure, and such rangesand subranges may be further delineated into relevant halves, thirds,quarters, fifths, and so on. As just one example, a range “of 150 to400” may be further delineated into a lower third, i.e., from 150 to233, a middle third, i.e., from 234 to 316, and an upper third, i.e.,from 317 to 400, which individually and collectively are within thescope of the appended claims, and may be relied upon individually and/orcollectively and provide adequate support for specific embodimentswithin the scope of the appended claims. In addition, with respect tothe language which defines or modifies a range, such as “at least,”“greater than,” “less than,” “no more than,” and the like, it is to beunderstood that such language includes subranges and/or an upper orlower limit. As another example, a range of “at least 0.1%” inherentlyincludes a subrange from 0.1% to 35%, a subrange from 10% to 25%, asubrange from 23% to 30%, and so on, and each subrange may be reliedupon individually and/or collectively and provides adequate support forspecific embodiments within the scope of the appended claims. Finally,an individual number within a disclosed range may be relied upon andprovides adequate support for specific embodiments within the scope ofthe appended claims. For example, a range of “1 to 9” includes variousindividual integers, such as 3, as well as individual numbers includinga decimal point (or fraction), such as 4.1, which may be relied upon andprovide adequate support for specific embodiments within the scope ofthe appended claims.

The subject matter of all combinations of independent and dependentclaims, both singly and multiply dependent, is expressly contemplatedbut is not described in detail for the sake of brevity. The disclosurehas been described in an illustrative manner, and it is to be understoodthat the terminology which has been used is intended to be in the natureof words of description rather than of limitation. Many modificationsand variations of the present disclosure are possible in light of theabove teachings, and the disclosure may be practiced otherwise than asspecifically described.

TABLE 1 Int. DMC Si Conv. Prod. Silicon Source Me₂HSiOMe Me₃SiOMeMeHSi(OMe)₂ Me₂Si(OMe)₂ MeSi(OMe)₃ TMOS “SiOSi” to Si Rate Cu₅Si′* 0 140 73 10 0 3 7.6 13.7 Cu₅Si^(‡)* 0 31 0 51 12 1 5 13.8 29.0 Cu₅Si^(†)* 05 0 15 39 40 1 1.3 2.3 (Cu_(0.99)Ti_(0.01))₅Si^(†) 2 14 0 36 28 20 0 0.91.6 (Cu_(0.99)Ni_(0.01))₅Si^(†) 0 6 0 16 39 39 0 0.3 0.6(Cu_(0.99)Al_(0.01))₅Si^(†) 0 0 0 0 0 0 0 0 0 Cu₅Si/SnCl₂ ^(†)° 7 13 070 9 0 1 2.1 3.5 In Table 1, * = same conditions were repeated threetimes, ^(‡) = copper silicide purchased Gelest; ′ = copper silicidepurchased from Alfa Aesar; ^(†) = copper silicide made according toReference Example 1 with high purity Si, Cu, and M; and ° = physicalmixture of Cu₅Si with 1000 ppm SnCl₂. TMOS refers to tetramethoxysilaneof formula Si(OMe)₄. Dimethyl carbonate was supplied at 2.6 sccm (0.01ml/min) and there was a 5 sccm Ar carrier gas. All reactions werecarried out at 350° C., 1 atmosphere pressure for 70 minutes. All valuesreported in (mol %) except the rate data with is represented in(μmol/min). Without wishing to be bound by theory, it is thought thatthe amount of Al was too high when incorporated in the copper silicideunder the conditions of example 1, and this resulted in the poorreactivity because too much Al may have decomposed the hydrocarbylcarbonate. It is thought that a lower amount of Al in the silicide wouldprovide beneficial results, based on the results of Table 2, below.

TABLE 2 Direct reaction of contact masses made with doped silicon,SnCl₂, and CuCl with DMC after 70 minutes at T = 350° C., P = 1 atm. Allvalues in (mol %) except for the rate, which is in (μmol/min). DMC Conv.Int. Si Sample Me₂HSiOMe Me₃SiOMe MeHSi(OMe)₂ Me₂Si(OMe)₂ MeSi(OMe)₃TMOS “SiOSi” to Si Prod. Rate 1 14 10 5 61 10 0 0 1.3 1.4 2 13 16 2 5613 0 0 1.5 1.6 3 9 17 1 58 15 0 0 1.3 1.4 4 4 14 6 62 13 1 0 0.8 0.8

In Table 2, in each example dimethyl carbonate was supplied at 2.6 sccm,Ar carrier was supplied at 5 sccm, 1 g Si metal was used, 176 mg CuClwas used, and 8 mg SnCl₂ was used. Sample 1 also contained 950 ppm Ti.Sample 2 also contained 1310 ppm Al. Sample 3 also contained 1100 ppm Tiand 1360 ppm Al. Sample 4 was prepared without additional Ti or Al.

1. A method comprises: 1) heating at a temperature of 150° C. to 400° C., ingredients comprising a) a hydrocarbyl carbonate, and b) a source of silicon and catalyst, where starting material b) is selected from the group consisting of copper silicide and a contact mass used in the Mueller-Rochow Direct Process, which comprises silicon metal and a catalyst such as copper; thereby forming a reaction product comprising an hydrocarbylhydrocarbyloxysilane of formula R_(a)H_(b)Si(OR)_((4-a-b)), where each R is independently a hydrocarbyl group and subscript a is 1 to 4 and subscript b is 0 to
 2. 2. The method of claim 1, where the hydrocarbyl carbonate is selected from dimethyl carbonate, diethyl carbonate, diphenyl carbonate, or methyl phenyl carbonate.
 3. The method of claim 1, where the catalyst comprises copper.
 4. The method of claim 1, where ingredient b) is a copper silicide.
 5. The method of claim 4, where the copper silicide is a binary copper silicide.
 6. The method of claim 4, where the copper silicide is Cu₅Si.
 7. The method of claim 4, where the copper silicide comprises copper, silicon and an additional metal selected from the group consisting of aluminium, tin, titanium, and combinations of two or more of aluminium, tin, and titanium.
 8. The method of claim 1, where ingredient b) comprises a contact mass comprising silicon and copper.
 9. The method of claim 8, further comprising adding d) a promoter.
 10. The method of claim 9, where the promoter comprises aluminium, tin, titanium, or a combination of two or more of aluminium, tin, and titanium.
 11. The method of claim 1, further comprising adding c) hydrogen during step 1).
 12. The method of claim 1, where each R is methyl, ethyl or phenyl.
 13. The method of claim 1, where the hydrocarbylhydrocarbyloxysilane comprises methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, and tetramethoxysilane.
 14. The method of claim 1, where the reaction product comprises a hydrocarbylhydrocarbyloxysilane of formula R₂Si(OR)₂.
 15. The method of claim 1, further comprising purging and/or treating ingredient b) before step 1) and/or 2) recovering the hydrocarbylhydrocarbyloxysilane from the reaction product.
 16. The method of claim 2, where ingredient b) is a copper silicide.
 17. The method of claim 2, where ingredient b) comprises a contact mass comprising silicon and copper. 